Wondrous Item, legendary (requires attunement by a Spending an hour with the item grants you visions letting you know what the item does.)
This is a full length cloak with a cowl which appears to be fashioned from darkness itself. If seen via detect magic or through another similar method one can see it has Illusory magic woven into the fabric.
Notes: Advantage: Stealth, Spending an hour with the item grants you visions letting you know what the item does.